The requirements for the chemical and technological properties of polymers which go on for processing have been substantially raised in recent times. This refers also to polyvinylalcohol (PVA). It is sufficient to say that temperatures of 220–240°C are frequently used to obtain special purpose fibres from PVA; at these temperatures, various degradation processes at the molecular level are unavoidable; chain rupture, increase in the degree of unsaturation, oxidation and so on. By the methods of electron spectroscopy it is possible to investigate such processes in PVA as dehydration and the formation of polyene systems, and to assess approximately the rate and degree of dehydration [1, 2]. But it is impossible to obtain from the data of the electronic spectra information about the presence of numerous impurities, in particular about those which exert a marked effect on the degradation process (for example, those which may act catalytically on the dehydration process). The problem set in the present work was to clarify the possibility of IR-spectroscopy for the analysis of thermal degradation and oxidation processes in PVA.